The “smoking/burning”, in other words, “smoldering”, means “flameless combustion”. This “flameless combustion” corresponds to a combustion mode exhibiting only a core of an internal flame with none of the sustained flame from the surface of the flammable matter in “flame combustion” (external flame and outside surface part of internal flame). In this smoldering region, flammable particles (grounds) receiving heat energy from the soaked flammable surface (top surface) obtain kinetic energy and rise up. Since no flame is accompanied with this, no oxidation reaction occurs. There is almost zero oxygen (air) consumption. The flammable matter gradually changes to a carbonizing layer by the internal flammable particles escaping from the flammable surface. Further, when the back surface (bottom surface) of this carbonizing layer ignites as a strong flame, this forms a soaking region (high heat region) for making the flammable matter itself smolder well from top to bottom. The carbonizing layer itself is converted to ash resulting in reduction of volume of the flammable matter. For this reason, the amount of oxygen required for reduction of the volume of the flammable matter (volume reduction rate 1/100 to 1/500) need only be the amount for conversion of the carbonizing layer to ash. Rather, due to the need to limit the supply of oxygen to prevent flame combustion, this is suitable as a containment volume reduction disposal method. Further, the flammable particles floating in the vessel deposit on the inside surface of the vessel as tar etc. for repeated smoldering. Also, by taking the dry distillation gas (smoldering gas) out from the vessel without burning or without discharge into the atmosphere, there are the merits that the gas can be made harmless or recycled by concentration and liquefaction or other final disposal.
However, the soaking region is covered by a solid carbonizing layer above it. Further, the soaking region slowly rises and does not remain at a constant position. Therefore, it is difficult to sustain the supply of oxygen to the soaking region. Until the flammable matter changes to a carbonizing layer, sufficient drying and dry distillation are necessary. For sustained smoldering, it is necessary to maintain a soaking region at the carbonizing layer under the flammable matter deposited in the sealed vessel. One of the conditions for maintaining this soaking region is locally raising the temperature (in a layer) and holding that high temperature by an oxidation reaction in the soaking region. To meet this latter condition, ceramic is laid at the bottom of the vessel and the flammable matter is deposited over it. Once a soaking region is formed at the interface between the ceramic layer and deposited flammable matter; the ceramic layer exhibits a heat storing action and heat radiating action. Further, some negative ions are generated. Due to this, the high temperature of the soaking region is sustained. Further, the ash produced accompanying the oxidation reaction of the carbonizing layer is sandwiched between the ceramic layer and soaking region, melts at the high temperature, and therefore is reduced in volume and gradually builds up in the ceramic layer as powder ceramic (substance similar to aero fins included in volcanic ash etc.), so the action by the ceramic cyclically accompanies the soaking region as it gradually moves upward region. The powder ceramic excessively increasing in the vessel can be taken outside of the vessel while leaving the part forming the ceramic layer and thereby can be recycled as useful matter.
On the other hand, to establish the former condition, it is necessary to blow a suitable amount of air into the vessel from the outside.
However, the technology for reducing the volume of the disposed matter in this smoldering apparatus in a sealed manner is disclosed in Japanese Patent Publication (A) No. 2004-136249 and Japanese Patent Publication (A) No. 2004-33966. Japanese Patent Publication (A) No. 2004-136249 describes blowing negative ion air generated by a plasma discharge type negative ion generator into a powder ceramic layer deposited on the bottom of a dry distillation vessel through negative ion intake ports in the horizontal direction so as to cause convection inside the powder ceramic layer. Further, it describes loading the disposed matter into the dry distillation vessel, then blowing in negative ion air and igniting the disposed matter from a residue discharge gate using an ignition burner etc. so as to lower the oxidation reduction potential inside the vessel by the negative ion air and create a reducing atmosphere for the start of smoldering. Further, Japanese Patent Publication (A) No. 2004-33966 blows negative ion air generated in a strong magnetic field of a permanent magnet through an air intake pipe from the center of the side of the dry distillation vessel to the inside of the vessel.
The significance of the blowing of the negative ion air is both the supply of a suitable amount of oxygen and the negative ion effect. The negative ion air enables the oxidation reduction potential inside the vessel to be reduced and a reducing atmosphere to be formed and enables flame combustion to be suppressed. In addition, in the soaking region, the particulate matter in the smoldering gas is vigorously generated as unstable positive ions, so the negative ions supplied from the outside and the Coulomb force quickly combine for an oxidation reaction which locally promotes a soaking region and sustains smoldering. Further, the particulate matter in the dry distillation gas floating above of the disposed matter is also positively charged, so if negative ions bond with and neutralize it, it declines in floating ability and easily aggregates. It therefore sinks down and settles in the vessel, is deposited on the inside surface of the vessel as tar etc., and again smolders, so it is possible to reduce the amount of gas led out from the vessel and raise the efficiency of the containment disposal.
Patent Document 1: Japanese Patent Publication (A) No. 2004-136249 (Paragraph No. 0030 to 0032, FIG. 1, FIG. 2)
Patent Document 2: Japanese Patent Publication (A) No. 2004-33966 (Paragraph No. 0019, 0021, FIG. 1, FIG. 2)